The effect of sodium on p-aminohippurate (PAH) transport kinetics was studied in isolated rat kidney slices in an attempt to define the role of sodium ion in renal organic acid transport. 1. In normally metabolizing renal slices, Na+ increased the Vmax of PAH influx without changing the Michaelis constant (Km). On the other hand, the effIux of preaccumulated PAH was reduced as the Na+ concentration increased. 2. In metabolically impaired renal slices, Na+ had no apparent effect on the influx and efflux of PAH. These results may indicate that Na+ is important for the energy transducing reaction in the PAH transport process.
Aminohippuric Acids/metabolism* ; Animal ; Biological Transport, Active/drug effects ; Culture Media ; Female ; In Vitro ; Kidney/metabolism* ; Kinetics ; Male ; Organ Culture ; Rats ; Sodium/pharmacology* ; p-Aminohippuric Acid/metabolism*

OBJECTIVETo explore the inhibitory effect and mechanism of rutin against platelet activating factor (PAF) induced platelet aggregation, 5-HT release and intra-platelet free calcium concentration.

METHODSThe rate of washed rabbit platelet (WRP) aggregation was measured by turbidimetry and O-phthaldialdehyde (OPT) fluoro-spectrophotometry (FSPM) was used to determine 5-HT content. The intraplatelet free calcium concentration was measured with Fura-2/AM FSPM assay.

RESULTSRutin in vitro was concentration-dependently inhibiting PAF (9.55 x 10(-9) mol/L) induced WRP aggregation, the IC50 of 5-HT release was 0.73, 1.13 mmol/L respectively and the intraplatelet free calcium concentration elevation evoked by PAF (4.78 x 10(-10) mol/L) were inhibited by 68.3, 136, 274, 545 mumol/L of rutin dose-dependently.

CONCLUSIONRutin could inhibit PAF induced platelet aggregation, 5-HT release and the increase of intraplatelet free calcium.

Animals ; Biological Transport, Active ; Blood Platelets ; metabolism ; Calcium ; metabolism ; Male ; Platelet Activating Factor ; antagonists & inhibitors ; Platelet Activation ; drug effects ; Platelet Aggregation Inhibitors ; pharmacology ; Rabbits ; Rutin ; pharmacology ; Serotonin ; metabolism

Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely: inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil (total or bioavailable concentration) that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include: soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity.
Biological Availability ; Biological Transport, Active ; Food Contamination ; analysis ; prevention & control ; Humans ; Metals, Heavy ; analysis ; pharmacokinetics ; toxicity ; Plants, Edible ; drug effects ; growth & development ; metabolism ; toxicity ; Soil Pollutants ; analysis ; pharmacokinetics ; toxicity ; Vegetables ; drug effects ; growth & development ; metabolism ; toxicity

The transmural heterogeneous changes of transient outward potassium currents (Ito) in rabbit hypertrophic cardiaomyocytes and the effects of long-term prophylactic treatment with volsartan were investigated. Rabbits were divided into hypertrophy group (left ventricular hypertrophy induced by partial ligation of abdominal aorta), vol-treated group (volsartan was administrated after the ligation), and control group (sham operated). Myocytes were isolated by a two-step enzymatical method. The sub-endocardial (Endo) and sub-epicardium (Epi) tissues were separated from midmyocardium (Mid) with a razor. Whole-cell patch-clamp technique was used to record potassium currents. The results showed that membrane capacitance was larger in hypertrophic cells than those in control and vol-treated cells (P<0.01 vs control cells, n=30). The densities of Ito in hypertrophic cells were reduced by sub-epicardium (Epi) (27.8 +/- 2.9) %, midmyocardium (Mid) (41.0+/-4.7) %, and sub-endocardium (Endo) (20.3 +/- 3.4) % compared with those in control cells. The decrease of Ito density was more pronounced in Mid than in Epi and Endo (P<0.01 vs Epi or Endo). There were no significant differences in Ito densities between vol-treated group and control group in three layers separately. In conclusion, volsartan can inhibit the transmural heterogeneous changes of Ito in left ventricular hypertrophic cardiomyocytes in rabbit.
Animals ; Antihypertensive Agents ; pharmacology ; Biological Transport, Active ; drug effects ; Female ; Hypertrophy, Left Ventricular ; drug therapy ; pathology ; Male ; Myocytes, Cardiac ; pathology ; Patch-Clamp Techniques ; Potassium Channels ; drug effects ; Rabbits ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

The metabolic transformation of the drugs containing carboxylic acid groups can lead to the formation of acyl glucuronide metabolites through catalysis by glucuronosyltransferase, and produce pro-acyl glucuronide intermediate metabolites with electronic activity. Then, protein or DNA adducts appeared after a series of non-enzyme or enzyme reactions. These adducts would change the protein activity and potentially lead to idiosyncratic and genotoxicity. In this paper, we discussed the chemical activity, drug-induced mechanisms, distribution and toxicity resulting from this metabolic activation for these drugs, and stated the status and prospects of research in this field.
Biological Transport, Active ; Biotransformation ; Carboxylic Acids ; metabolism ; toxicity ; DNA Damage ; drug effects ; Drug-Related Side Effects and Adverse Reactions ; Glucuronides ; metabolism ; toxicity ; Glucuronosyltransferase ; metabolism ; Hepatocytes ; metabolism ; Humans ; Pharmaceutical Preparations ; metabolism

By using Fura-2/AM, the effects of magnesium (Mg2+) on the glutamate-induced increase of intracellular free calcium ([Ca2+]i) in the cultured hippocampal neurons and the features were investigated by integrated photoelectric detecting system. The experiments were designed to three groups (The drug was spit to the cells for 20 s): Group A receiving 1 x 10(-5) mol/L glutamate; Group B receiving 1 x 10(-5) mol/L glutamate and 1 x 10(-5) mol/L Mg2+ simultaneously; Group C receiving 1 x 10(-5) mol/L glutamate again after [Ca2+]i in group B back to the baseline. The results showed that in group A, [Ca2+]i was obviously increased. In group B, the changes in [Ca+] i and the peak value were significantly decreased. Moreover, the elevation of Phase 1 was slowed down and Phase 2 was shortened to some extent, and the plateau phase between them was relatively prolonged. In group C, calcium oscillation similar to that in group A occurred, but both the Phase 1 and Phase 2 were shortened and the delta[Ca2+]i was slightly decreased. It was suggested that Mg2+ could quickly inhibit the rise of [Ca2+]i induced by glutamate in the cultured hippocampal neurons in rats.
Animals ; Animals, Newborn ; Biological Transport, Active ; drug effects ; Calcium ; metabolism ; Cells, Cultured ; Fura-2 ; pharmacology ; Glutamates ; pharmacology ; Hippocampus ; cytology ; metabolism ; Magnesium ; pharmacology ; Neurons ; cytology ; metabolism ; Rats ; Rats, Sprague-Dawley

The effects of Arecoline (Are) on calcium mobilization were investigated. In isolated single ventricular myocyte of guinea pig, patch clamp whole cell recording techniques were used to record the current of L-type calcium channel and cytosolic Ca2+ level ([Ca2+]i) labeled with fluorescence probe Fluo-3/AM was measured under a laser scanning confocal microscope. Results revealed that Are (3-100 mumol/L) could inhibit L-type calcium current in a concentration-dependent manner and the value of IC50 was 33.73 mumol/L (n = 5). In the absence of extracellular calcium, the resting levels of [Ca2+]i was not affected by Are (n = 6, P > 0.05), but pretreatment with Are (30 mumol/L) could significantly inhibit the [Ca2+]i elevation induced by caffeine (10 mmol/L, n = 6, P < 0.01). It was concluded that Are could inhibit not only calcium influx through L-type calcium channel but also calcium release from sarcoplasmic reticulum.
Animals ; Arecoline ; pharmacology ; Biological Transport, Active ; Caffeine ; pharmacology ; Calcium ; metabolism ; Calcium Channels, L-Type ; drug effects ; metabolism ; Cell Separation ; Cholinergic Agonists ; pharmacology ; Guinea Pigs ; Heart Ventricles ; cytology ; Myocytes, Cardiac ; cytology ; metabolism ; Patch-Clamp Techniques ; Sarcoplasmic Reticulum ; metabolism

The key points for better protection of trehalose in freeze-drying red blood cells (RBCs) are to resolve non-osmosis of trehalose to red blood cells and to make cytoplasmic trehalose to reach effective concentration. This study was aimed to investigate the regularity of loading RBCs with trehalose, screen out optimal loading condition and evaluate the effect of trehalose on physico-chemical parameters of RBCs during the period of loading. The cytoplasmic trehalose concentration in red blood cells, free hemoglobin and ATP level were determined at different incubation temperatures (4, 22 and 37 degrees C), different trehaolse concentrations (0, 200, 400, 600, 800 and 1000 mmol/L) and different incubation times (2, 4, 6, 8 and 10 hours), the cytoplasmic trehalose, free hemoglobin (FHb), hemoglobin (Hb) and mean corpuscular volume (MCV) in fresh RBCs and RBCs stored for 72 hours at 4 degrees C were compared, when loading condition was ensured. The results showed that with increase of incubation temperature, time and extracellular trehalose concentration, the loading of trehalose in RBCs also increased. Under the optimal loading condition, cytoplasmic trehalose concentration and free hemoglobin level of fresh RBCs and RBCs stored for 72 hours at 4 degrees C were 65.505 +/- 6.314 mmol/L, 66.2 +/- 5.002 mmol/L and 6.567 +/- 2.568 g/L, 16.168 +/- 3.922 g/L respectively. It is concluded that the most optimal condition of loading trehalose is that fresh RBCs incubate in 800 mmol/L trehalose solution for 8 hours at 37 degrees C. This condition can result in a efficient cytoplasmic trehalose concentration. The study provides an important basis for long-term preservation of RBCs.
Biological Transport, Active ; drug effects ; Blood Preservation ; methods ; Cryopreservation ; methods ; Cryoprotective Agents ; metabolism ; pharmacology ; Erythrocyte Membrane ; metabolism ; Erythrocytes ; Freeze Drying ; Humans ; Osmotic Fragility ; Temperature ; Time Factors ; Trehalose ; metabolism ; pharmacology

Annexin A2, a multifunctional tumor associated protein, promotes nuclear factor-kappa B (NF-κB) activation by interacting with NF-κB p50 subunit and facilitating its nuclear translocation. Here we demonstrated that two ginsenosides Rg5 (G-Rg5) and Rk1 (G-Rk1), with similar structure, directly bound to Annexin A2 by molecular docking and cellular thermal shift assay. Both Rg5 and Rk1 inhibited the interaction between Annexin A2 and NF-κB p50 subunit, their translocation to nuclear and NF-κB activation. Inhibition of NF-κB by these two ginsenosides decreased the expression of inhibitor of apoptosis proteins (IAPs), leading to caspase activation and apoptosis. Over expression of K302A Annexin A2, a mutant version of Annexin A2, which fails to interact with G-Rg5 and G-Rk1, effectively reduced the NF-κB inhibitory effect and apoptosis induced by G-Rg5 and G-Rk1. In addition, the knockdown of Annexin A2 largely enhanced NF-κB activation and apoptosis induced by the two molecules, indicating that the effects of G-Rg5 and G-Rk1 on NF-κB were mainly mediated by Annexin A2. Taken together, this study for the first time demonstrated that G-Rg5 and G-Rk1 inhibit tumor cell growth by targeting Annexin A2 and NF-κB pathway, and G-Rg5 and G-Rk1 might be promising natural compounds for targeted cancer therapy.
Active Transport, Cell Nucleus ; drug effects ; Annexin A2 ; chemistry ; deficiency ; genetics ; metabolism ; Antineoplastic Agents ; chemistry ; metabolism ; pharmacology ; Apoptosis ; drug effects ; Biological Products ; chemistry ; metabolism ; pharmacology ; Cell Nucleus ; drug effects ; metabolism ; Down-Regulation ; drug effects ; Drug Discovery ; Gene Knockdown Techniques ; Ginsenosides ; chemistry ; Hep G2 Cells ; Humans ; Molecular Docking Simulation ; Molecular Targeted Therapy ; NF-kappa B p50 Subunit ; metabolism ; Protein Conformation

To study the effects of major components of Maijunan tablets, puerarin (Pue) and rhynchophylline (Rhy) on the transport of hydrochlorothiazide (Hct) Caco-2 cell monolayer model, the transport parameters of Hct, such as apparent permeability coefficient (P(app) (B --> A) and P(app) (A --> B)) and the ratio of P(app) (B --> A) versus P(app) (A --> B), were studied and compared when Hct was used solely and co-used with Pue and/or Rhy. The effects of drug concentrations, conveying times, P-glyprotein (P-gp) inhibitor verapamil and conveying Liq pH values on the transport of Hct in the above conditions were also investigated. The results indicated that the absorption of Hct in Caco-2 cell monolayer model could be a carrier-mediated active transport, along with the excretion action mediated by P-gp. Pue can decrease the excretion action of Hct mediated by P-gp, and Rhy had no significant effect on the transport of Hct. The co-use of Hct, Pue and Rhy enhanced the absorption of Hct. Meanwhile, conveying Liq pH value had significant influence on the transport of Hct. The absorption of Hct at pH 6.0 was higher than that at pH 7.4.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; Absorption ; drug effects ; Biological Transport, Active ; drug effects ; Caco-2 Cells ; Drugs, Chinese Herbal ; administration & dosage ; isolation & purification ; pharmacology ; Humans ; Hydrochlorothiazide ; pharmacokinetics ; Hydrogen-Ion Concentration ; Indole Alkaloids ; administration & dosage ; isolation & purification ; pharmacology ; Isoflavones ; administration & dosage ; isolation & purification ; pharmacology ; Plants, Medicinal ; chemistry ; Time Factors ; Vasodilator Agents ; administration & dosage ; isolation & purification ; pharmacology ; Verapamil ; pharmacology